The present invention is directed towards an audible sensor. More specifically, the present invention is directed towards a sensor for an air filter to indicate a replacement thereof.
Heating and cooling systems for houses and other dwellings and for at least some commercial establishments include a system for transmitting heated or cooled air throughout the dwelling or commercial establishment. These systems for transmitting heated or cooled air also include filtration equipment for removing particulate matter from the heated or cooled air and this filtration equipment, particularly for dwellings, normally includes one or more mechanical filters formed from fibrous materials.
These filter materials serve the function of mechanically blocking particulate matter that is in the air flowing in circuitous paths through the filter material. The particulate matter becomes attached to individual fibers and, over a period of time, progressively restricts the air flow paths. This trapped particulate matter simultaneously causes a reduction of the air flow rate through the filter.
This reduced air flow rate reduces the efficiency of the heating or cooling system and the effective heating or cooling of the dwelling or commercial establishment. The partially clogged filter also causes increased back pressure to be applied to the blower or fan which generates the air flow and this back pressure increases the work that must be performed and the energy consumed by the blower or fan unit. The resulting increased load increases the wear rate of the moving parts in the heating or cooling system and also results in increased operating costs.
In order to determine when an air filter needs to be changed, a person normally must gain access to the filter. The filter must then be removed and visually inspected. If it is evident through this visual inspection that there is a significant build up of particulate matter on the outside surface of the air filter it is usually replaced with a new filter. This procedure has various deficiencies. This procedure means that the air filter must be periodically checked in order to determine when the filter needs to be changed. This is time consuming and can often result in dirty filters not being changed on time due to the failure to remember to check the filter.
U.S. Pat. No. 4,215,646 to Williams describes a whistle audibly responsive to extremely small pressure differentials. The whistle comprises an inlet portion of a first diameter and an outlet portion of a second diameter. The whistle produces an audible sound when a pressure differential exists across the inlet and outlet portions.
U.S. Pat. No. 5,352,255 to Taft describes a noise maker apparatus for an air filter. The noise maker has a housing having a hole and a weighted member in resilient relationship over the hole. The weighted member is responsive to a pressure change across the hole.
However, the replacement of air filters may be a function of time. More specifically, air filters may be replaced based upon a manufacturer's suggested time. To that, there is a need for an improved sensor for air filters.